body{
  width: 100%;
  height: 100vh;
  box-sizing: border-box; 
  padding: 20px;
  margin: 0;
  overflow: hidden;
}

main{
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  height: 100%;
}

.msgbox{
  height: 78%;
  width: 100%;  
  padding: 10px;
  box-sizing: border-box;
  border: 2px solid rosybrown;
  background-color: darkkhaki;
  overflow: hidden;
}

textarea{
 height: 20%;
 width: 100%;
 box-sizing: border-box;
 border: 2px solid rosybrown;
 padding: 10px;
 background-color: #eee;
 font-size: 18px;
 outline: none;
}

.msg{
  display: flex;
  justify-content: space-between;
  margin-bottom: 20px;
}
.msg section{
   flex: 1;
   background-color: #fff;
   padding: 10px;
   position: relative;
   word-break: break-all;
}
.left section{
  margin-left: 15px;
}
.right section{
  margin-right: 15px;
}
.left section::after{
  content: "";
  width: 0;
  height: 0;
  position: absolute;
  border: 8px solid transparent;
  border-right-color: #fff;
  left: -16px;
  top: 10px;
}
.right section::after{
  content: "";
  width: 0;
  height: 0;
  position: absolute;
  border: 8px solid transparent;
  border-left-color: #fff;
  right: -16px;
  top: 10px;
}

.tips{
  position: fixed;
  padding: 10px;
  background-color: rgba(0,0,0,0.4);
  color: #eee;
  left: 50%;
  top: 50%;
  font-size: 18px;
  transform: translate(-50%, -50%);
  -webkit-transform: translate(-50%, -50%);
  display: none;
}